The present invention relates to a process of extracting hydrocarbons from a tar sand. More specifically, the present invention relates to the extraction of hydrocarbons from a diatomite hydrocarbon-rich ore.
Diatomite-hydrocarbon ores and similar materials are different from the vast majority of grainy or sand-like tar sands. Diatomite ores are composed of hollow silicaceous skeletons of single-celled animals referred to as "diatoms." A diatomite-like ore is defined as a material which has a surface area and structure which is substantially similar to diatomaceous earth. In ocean sediments, hydrocarbon-rich diatomaceous earth is sometimes referred to as "diatom ooze" which is normally found at a depth of about 1500 fathoms and comprises the empty shells of diatoms. The porous structure and extremely high surface area of diatomaceous earth makes extraction and recovery of the hydrocarbons difficult. Although diatomite ore is sometimes classified as a tar sand, i.e., sand cemented by a bitumen too viscous to be recovered by conventional crude oil production methods, the properties of the ore preclude application of most hydrocarbon solvent or hot water-wash techniques. Solvents which displace the hydrocarbons tend to be trapped in the diatomaceous earth structure, thus rendering recovery uneconomical. Steam or aqueous hot-wash techniques have difficulty reaching the surface of the diatomaceous ore to remove the hydrocarbons therefrom. Thus, it would be highly desirable to have a process which can extract the hydrocarbons from the diatomaceous ore or diatomaceous-like ore without entraining diatoms in the extracted hydrocarbons and wherein the solvent and the extracted hydrocarbons are easily separable and the solvent can be reused in the recovery process.